The purpose was to determine the relationship between glucose intolerance and mitochondrial DNA mutations in the region of the common age-related 4977 base pair deletion. 22 volunteers were studied during the reporting period. An abstract was presented at the Experimental Biology Meeting in April 1996 and a manuscript is presently under review. The results suggest that there is an increase in the different types and frequency of mtDNA deletions in older individuals with impaired glucose tolerance or diabetes mellitus.